Lactic acid, a chemical responsible for muscle fatigue, is a monoprotic acid. When 0.578 g of lactic acid is titrated with 0.206 M NaOH, a volume of 31.11 mL of NaOH is used. What is the molar mass of lactic acid?
HA + NaOH > NaA + H2O
(also does the A represent acid?)
Yes, the problem says lactic acid is a monoprotic acid so we write H for the acid part and A for the rest of the large molecule. It makes typing easier. The molar mass of lactic acid is 90.08.
mols HA = grams/molar mas = 0.578/90.08 = approx 0.006 but you should use a more accurate number.
mols NaOH = M x L = approx 0.006
Look at the equation and you can see that 1 mol HA = 1 mol NaOH; therefore, mols HA must be approx mols NaOH or 0.007.
Then M HA = mols HA/L HA.
Post your work if you get stuck.
Yes, in this reaction, A represents the anion of the acid, which is lactate in this case.
To find the molar mass of lactic acid (HA), we can use the given information and the equation of the reaction.
First, let's calculate the number of moles of NaOH used:
moles of NaOH = volume of NaOH (in L) x concentration of NaOH (in mol/L)
= 31.11 mL x (1 L / 1000 mL) x 0.206 mol/L
= 0.00640 mol
Since lactic acid (HA) is a monoprotic acid, it reacts with 1 mole of NaOH:
moles of lactic acid (HA) = moles of NaOH
Now, we can calculate the molar mass of lactic acid (HA):
molar mass of lactic acid (HA) = mass of lactic acid (g) / moles of lactic acid (HA)
= 0.578 g / 0.00640 mol
= 90.3 g/mol
Therefore, the molar mass of lactic acid is 90.3 g/mol.
To find the molar mass of lactic acid, we can use the information provided in the titration.
In a titration, a known volume and concentration of a solution (in this case, 0.206 M NaOH) is reacted with a known mass of the compound being analyzed (in this case, lactic acid). The reaction equation you have given is:
HA + NaOH → NaA + H2O
In this equation, HA represents the lactic acid, and A represents the conjugate base of the acid.
From the balanced equation, we can deduce that the stoichiometric ratio between lactic acid (HA) and sodium hydroxide (NaOH) is 1:1. This means that 1 mole of lactic acid reacts with 1 mole of sodium hydroxide.
First, let's calculate the number of moles of NaOH used in the titration:
moles NaOH = (volume of NaOH used in L) * (concentration of NaOH in mol/L)
= 0.03111 L * 0.206 mol/L
= 0.006415 mol
Since the stoichiometric ratio between lactic acid and NaOH is 1:1, the number of moles of lactic acid (HA) is also 0.006415 mol.
Now, we can calculate the molar mass of lactic acid using the formula:
molar mass of lactic acid = (mass of lactic acid used in g) / (number of moles of lactic acid)
Substituting the values:
molar mass of lactic acid = 0.578 g / 0.006415 mol
= 90.13 g/mol
So, the molar mass of lactic acid is approximately 90.13 g/mol.
Yes, in the given reaction equation, 'A' represents the conjugate base of the acid lactic acid (HA).